It is meant to be used with files displayed in loading order. It cannot be undone (at least, not in a single step). This command will update the time of selected files, starting from current system time, keeping the same plugin order. For anybody interested in including TESTools-like (based on redating selected mods relative to current system time/first selected mod timestamp) mod reordering in Mash, you can find a example of changes to the masher.py file to add (right click option/description):
